Dysgeusia, the proposed studies will correlate psychophysical and histological changes in gustation during and following irradiation of the oral cavity. Since the detailed psychophysical testing will involve the anterior part of the tongue, histological analysis will focus on fungiform papillae. The experiments will compare the number of stainable taste pores observed in vivo to the psychophysical data. Biopsies of fungiform papillae will permit immunochemical analysis of taste buds. Established immunochemical markers of taste bud differentiation, i.e. gustducin and cytokeratin-19, will be used. These techniques will be applied to patients receiving irradiation to the oropharyngeal region as therapy for squamous cell carcinoma of the head and neck and to age-matched controls. Biopsy of taste papillae from the patients will be timed to coincide with the decline and recovery of gustatory sensitivity during and after radiation treatment. Subjects identified in the Ear, Nose and Throat Department at University Hospital will be tested for gustatory function prior to, during, and after radiation treatment. Detection thresholds will be measured globally (whole mouth) and locally (dorsal anterior surface of the tongue). Each subject will be tested with two of four tastants: sodium chloride, sucrose, citric acid and quinine sulfate. In this manner we will determine whether radiation produces similar degrees of sensitivity loss in all taste qualities and in response to similar radiation doses. Histochemical evaluation of taste buds will allow us to correlate the degree of taste loss with histological and cytochemical changes in the taste buds from the tested area of the tongue.